Double walled combustion chamber



Dec. 6, 1960 D. N. GOLDSTEIN DOUBLE WALLED COMBUSTION CHAMBER Filed July 23, 1957 INVENTOR.

BY W l Unit DOUBLE WALLED COMBUSTION CHAMBER Filed July 23, 1957, Ser. No. 673,750

2 Claims. (Cl. 6039.65)

This invention relates to a means for providing operating fluid for use by a starter motor for a prime mover and is more particularly concerned with a combustion chamber for receiving a fuel-air mixture for transmission to said motor.

A combustion starter is designed to operate on the hot gas products derived from a mixture of compressed air and an engine fuel. The two constituents are introduced into a combustion chamber where the mixture is fired by a spark device. The resultant hot gases are then directed to a starter assembly. However, due to the extremely high temperatures of the fired gas, two major problems have arisen. These are the unduly hot surfaces occurring in the combustion chamber and the thick walls thereof necessary to withstand the stresses caused by the elevated temperatures.

Accordingly, it is a primary object of this invention to provide a design for combustion chambers which will eliminate the problem of extremely hot exposed surfaces on such chambers.

Another primary object of my invention is to provide such a chamber in which the thickness of the wall, and consequently the weight of the chamber, can be materially reduced.

The above and still further objects of my invention will become apparent upon consideration of the following detailed description thereof, especially when taken in conjunction with the accompanying drawings, in which:

Figure 1 is a plan view of a combustion chamber incorporating the invention; and

Figure 2 is a sectional elevation of the chamber shown in Figure l, the section being taken on the lines AO-- BO-CO in the direction of the arrows.

Turning specifically to the drawings in which like characters of reference indicate like parts, a combustion chamber is generally indicated at 10. Said chamber has an outer cylindrical wall 12 and an inner cylindrical wall 14 concentric therewith. Formed between said cylinders is an annular chamber 16. A main fuel combustion chamber 18 is formed within the inner cylinder 14.

The upper ends of the cylinders 12 and 14 are closed by a cover plate 20. This plate is formed with a dependent ridge 22 at its outer periphery, said ridge fitting into the annular chamber 16. A central boss 24 on the plate 20 is internally threaded to receive a nozzle assembly. Such an assembly comprises a hollow plug 26 with an external thread cooperable with the threaded boss. The plug also has an internal thread for reception of a nozzle member 28'. This latter threaded connection permits simple interchanging of various sizes and shapes of nozzles.

The lower ends of said cylinders are closed by an apertured plate 30. A tubular extension 32 is formed integrally with the plate 30 and extends into the chamber 18. Said extension terminates in an internal annular flange 34. The plate 30 has an internal thread which coacts with an external thread on an annular cap 36. .A sleeve 38 having a plurality of ports 40 therein is Z,%Z,Z Patented Dec. 6, 1960 clamped between said cap 36 and the flange 34 on the plate 30. A nozzle member 42 is threaded into the central opening in the cap 36. Both of the member 26 and 36 are adapted to receive fuel lines whereby nozzles 28 and 42 will act to meter the entrance of fuel into the chamber 18 for mixture and firing.

The second component of the mixture to be fired is compressed air, and this is supplied from a tank or other suitable source partially shown at 44. A line 46 leads from the tank 44 to a coupling 48 of any conventional type. Said coupling connects line 46 to an inlet pipe 50 which passes through aligned apertures in the cylinders 12 and 14, and is finally threaded into an opening in the tubular extension 32 of the plate 30. A supplemental line 52 communicates with the line 46 between the source 44 and the coupling. Said supplemental line passes through the outer cylinder 12, and serves to supply compressed air to the annular chamber 16. A needle valve 54 in said line in adjustable to permit easy regulation of the amount of air entering the chamber 16.

Exit from the main fuel chamber and the annular chamber 16 is provided by an outlet conduit 56. An arcuate portion of the cylinder wall 12 is broken away, and an aperture plate 58 is substituted therefor. The conduit 56 passes through said plate 58 and also through the cylinder wall 14. A series of ports 66 (only one shown) permits the annular chamber 16 to communicate with the outlet conduit.

In operation, fuel is fed into the chamber 18 from either one or both of the nozzle 28 and 42. Compressed air from the source 44 also enters said chamber via the lines 46 and 5t), and the ports 49 in the member 38. At the same time, a portion of the air is by-passed through the line 52 and into the annular chamber 16. The flow to this chamber is controlled by adjustment of the valve 54. Any suitable spark device (not shown) is then used to fire the mixture in the main chamber. Such a device would enter the chamber by insertion through a boss 62 formed integrally with the side wall of cylinder 12. The hot gas products pass out via outlet 56 and are directed to a turbine starter assembly.

The use of the air-filled chamber 16 has been found to produce the advantages sought after. Using my invention it is possible to touch the outer wall directly after a full firing. In addition, after firings, a visual inspection of the inner surface of the cylinder 14 showed no signs of erosion or cracking. Further, although air from the main line has been by-passed for use as a coolant, such air is not wasted. Since in currently used single walled chambers some air is by-passed to dilute the fired product at the exit, the air from chamber 16 is also used as a diluent. It enters the outlet line through the ports 60. The use of the valved, supplemental line 52, also eliminates the need for nozzle changes when it is found desirable to alter the ratio of hot gas product to diluent air in the outlet.

It is to be understood that the above-described arrangement is merely illustrative of the applications of the principles of my invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. Means for producing operating fluid. for use in a starting motor comprising a first tubular member, a second tubular member surrounding said first member and concentric therewith, closure means for opposite ends of each of said members, means for introducing fuel into said first member, outlet means from said first member, a source of compressed air, second inlet means connected with said source for introducing compressed air into said first member, spark-producing means associated with said first member for firing a mixture of said fuel and compressed'air, by-pass means connected between said-secondary inlet means and the annular chamber between said members,*port means connecting said chamber to said outlet at a point outside of said first tubular, member, and valve means in said -by-pass'means forregulating the flow of air therethrough.

2. Means for providingoperating fluid for use in starting motors comprising a first cylinder having a main chamber formed therein, a second cylinder surrounding said first cylinder and forming an annular chamber therebetween, means common to both of said cylinders for closing one end thereof, means for closing the other end of each of said cylinders, a fuel inlet passing through each of said means to said main chamber, a source of compressed air, an air inlet connecting said source with said main chamber, a supplemental line connected between said source and said annular chamber, adjustable valve means insaid supplemental line, and outletmeans communicating with both of said chambers, said outlet means being connected to said annular chamber at a 5 point outside said main chamber.

References Cited in the file of this patent UNITED STATES'PATENTS 710,130 Weiss Sept. 30, 1902 10 2,528,330 Heppner Sept. 30, 1947 2,616,252 Robinson et a1. Nov. 4, 1952 2,648,950 Miller Aug. 18, 1953 2,858,672 Clark Nov. 4, 1958 FOREIGN PATENTS 230,332 Switzerland Mar. 16, 1944 

